”libMagickWand.so.1: cannot open shared object file

This message is extremely confusing. It looks like Ruby is complaining that it can’t find RMagick.so, but actually Ruby is complaining that it can’t find libMagickWand.so.

http://rmagick.rubyforge.org/install-faq.html#libmagick

export LD_LIBRARY_PATH=/usr/local/lib

すればOK。